Practicing one component in one time to learn the whole

Most often questions are designed that tests the understanding of whole instead of its components. Students miserably fail to solve these problems due to lack of enough practice of its components.

So systematically breaking down the whole concept into its required components is important.
e.g. Take this question:
[Cr(NH3)6]3+ is paramagnetic while [Ni(CN)4]2- is diamagnetic. Explain why?

To start solving this question you have to know the following components:
1) You have to know the atomic number of Cr and Ni. If you have forgotten the atomic number or not memorized it, you are out of luck to solve it.
So, has the teacher or the book has given memory tricks to memorize the periodic table.
2) After you know the atomic number, do you know the electronic configuration of the metal atom?
3) Then, can you determine the electronic configuration of metal ion?
4) Do you know how to calculate the oxidation state, because you need to calculate the charge of metal ion?
5) Have you memorized the charge of different ligands?
6) Do you know the spectrochemical series, which of the ligands are the weak field or strong field?
7) Do you know which of the ligands bidentate and polydentate?
8) Can you predict the geometry and hybridization based upon the attached ligands?
9) Do you know the d orbital splitting for a different type of geometry (i.e. what will be the splitting pattern of octahedral and square planar geometry.)
10)Can you know whether it's a square planar geometry or tetrahedral geometry based upon metal ion electronic configuration?
11) Do you know how to fill the orbitals with electron based on splitting energy?
12) Do you know what is diamagnetic (i.e. with no unpaired electron) and what is paramagnetic (i.e. with a unpaired electron)?

So after you have practiced all these components you will be able to solve this question.

This component approach learning can be seen in organic chemistry book:
Organic Chemistry as a Second Language by David Klein

Concepts are broken into components, and enough exercises are given for practice for each component, and at the end of the chapter, questions that require comprehension of the whole is presented.

Take this question:
Which one of the following has the highest dipole moment?
(i) CH2Cl2
(ii) CHCl3
(iii) CCl4

The explanation given is this:

The diagram here is completely wrong, as it shows atoms are placed in single plane.

The components are:
What is the hybridization and molecular shape of these molecules?

How to calculate the vector sum? (CH2Cl2 and CHCl3 is confusing, requires computation of vector sum) Is the computation of vector sum demonstrated in the class?

Some suggestions for effective component practice:
  • Give students an example solved problems before asking them to solve.
  • Don't give the same type of questions for each component, always twist the question a little, so that it requires same problem-solving approach in a different situation, or requires little more information or little different information to solve. Just changing the given values of a question is not a different situation.
  • Interleave between questions of different components, if they have similarities and associative dissimilarities so that they can identify the patterns and transfer learning in different context.
  • Don't ask to repeat questions, until they begin to forget it, it takes away student time for doing fruitless work. Use spaced learning instead. 

Why component system works? (Cognitive Load Theory)


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